Method and apparatus for providing an interface mechanism for a computer simulation

1. An interface mechanism providing motion in at least two degrees of freedom for a user and interfacing said motion with a computer, said interface mechanism comprising: a linkage mechanism including a plurality of members pivotably coupled to each other and providing two revolute degrees of freedom about a pivot point located remotely from said plurality of members, said pivot point located at about an intersection of axes of rotation of at least two of said members; a user manipulatable object coupled to at least one of said plurality of members, said user manipulatable object being rotatable in said two revolute degrees of freedom about said pivot point; and at least one sensor reading said rotation of said user manipulatable object and providing at least one sensor signal indicating a position of said user manipulatable object in said two revolute degrees of freedom, wherein said computer receives an indication of said position.

2. An interface mechanism as recited in claim 1 wherein said plurality of members includes five members coupled in a closed loop such that each of said five members is pivotably coupled to two other members of said five members.

3. An interface mechanism as recited in claim 1 wherein said plurality of members are positioned exclusively on one side of said pivot point, wherein said members are provided within a hemisphere of a sphere defined such that said pivot point is at a center of said sphere and said user manipulatable object can be moved in a workspace that defines at least at portion of a surface of said sphere.

4. An interface mechanism as recited in claim 3 wherein at least a portion of said user manipulatable object extends through said pivot point.

5. An interface mechanism as recited in claim 1 wherein said user manipulatable object is independently translatable with respect to said linkage mechanism along a linear third axis in a third degree of freedom through said pivot point.

6. An interface mechanism as recited in claim 1 wherein said at least one sensor is a plurality of sensors, each of said sensors coupled between two of said members of said linkage mechanism for an associated degree of freedom, said sensors being coupled to said computer system.

7. An interface mechanism as recited in claim 1 further comprising a plurality of actuators, each of said actuators coupled between two of said members of said linkage mechanism for an associated degree of freedom, each of said actuators providing a force on said user manipulatable object in an associated degree of freedom.

8. An interface mechanism as recited in claim 7 further comprising a band drive mechanism coupled between one of said actuators and one of said members, said band drive mechanism transmitting said force generated by said actuator to said user manipulatable object and transmitting movement applied to said user manipulatable object by a user to said sensors.

9. An interface mechanism as recited in claim 8 wherein said band drive mechanism includes a rotating drum rotatably coupled to one of said members and rigidly coupled to another one of said members, said drum being additionally coupled to a spindle by a flat band, wherein said transducer is operative to rotate said spindle and thereby rotate said drum and transmit force to said rigidly-coupled member with substantially no backlash.

10. An interface mechanism for interfacing motion with a computer system, said interface mechanism comprising: a plurality of members movable with respect to each other for providing at least one degree of freedom to a user manipulatable object; an actuator operative to provide a force in one of said degrees of freedom of said user-manipulable object; a sensor operative to provide positions of said user-manipulatable object in said at least one degree of freedom; and a band drive mechanism including a capstan and a flat band, said capstan coupled to a particular one of said members and to a rotating shaft of said actuator, wherein said flat band is coupled to said capstan at a first end of said band and coupled to said particular member at a second end of said band, wherein said capstan is coupled to said particular member by said flat band such that force is applied to said particular member in said at least one degree of freedom when said rotating shaft of said actuator is rotated.

11. An interface mechanism as recited in claim 10 wherein said force is applied to said particular member in a linear degree of freedom.

12. An interface mechanism as recited in claim 10 wherein said force is applied to said particular member in a rotary degree of freedom.

13. An interface mechanism as recited in claim 10 wherein said flat band includes two separate bands, wherein each of said bands is coupled to said capstan at first ends and each of said bands is attached to said particular member at a second end.

14. An interface mechanism as recited in claim 12 further comprising a drum rigidly coupled to said particular member and rotatably coupled to another one of said plurality of members, wherein said capstan is coupled to said drum by said flat band.

15. An interface mechanism as recited in claim 14 wherein said particular member is one of five rotatably coupled members provided in a closed loop chain such that each of said members is rotatably coupled to two others of said members.

16. An interface mechanism as recited in claim 15 wherein said plurality of members provide two revolute degrees of freedom to said user manipulatable object about a pivot point located remotely from said plurality of members, said pivot point located at about an intersection of axes of rotation of said members.

17. An interface mechanism as recited in claim 16 wherein said user manipulatable object extends through said pivot point and is movable in said two degrees of freedom.

18. An interface mechanism as recited in claim 17 wherein said user manipulatable object is coupled to a linear axis member, wherein said user manipulatable object and said linear axis member are movable in a third linear degree of freedom.

19. An interface mechanism as recited in claim 18 further comprising a second band drive mechanism including a second capstan and a second flat band, said second capstan coupled to said linear axis member by a flat band and to a rotating shaft of said actuator, such that force is applied to said user manipulatable object in said third linear degree of freedom when said rotating shaft of said actuator is rotated.

20. An interface mechanism as recited in claim 18 wherein said linear axis member is a slide portion of a linear bearing.

21. An interface mechanism as recited in claim 10 wherein said computer system implements a medical simulation and wherein said user-manipulable object is a medical instrument.

22. An interface mechanism as recited in claim 21 wherein said user manipulatable object includes a needle and syringe, and wherein said medical simulation simulates an epidural anesthesia procedure of inserting said needle into tissue, where forces are provided on said needle to realistically simulate said insertion.

23. A method, comprising: receiving sensor data from a sensor included on an interface apparatus, the sensor data indicating a position of a manipulatable object in a degree of freedom, the degree of freedom being one of a first rotary degree of freedom, a second rotary degree of freedom and a linear degree of freedom, the interface apparatus including a gimbal, the manipulatable object being movable in the first rotary degree of freedom and the second rotary degree of freedom in a spherical workspace and configured to be rotated about a pivot point spaced apart from the gimbal, the pivot point being located at a center of a sphere defined by the spherical workspace, the manipulatable object further configured to be moved in the linear degree of freedom through said pivot point; selecting a physical property profile from a plurality of available physical property profiles based on the position of manipulatable object; and outputting a force on the manipulatable object via an actuator included in the interface apparatus, the force output on the manipulatable object being determined, at least in part, from a physical property value of the selected physical property profile.

24. The method of claim 23 , wherein the degree of freedom is a linear degree of freedom.

25. The method of claim 23 , wherein the selection of the physical property profile from the plurality of available physical property profiles is further dependent on a direction of movement of the manipulatable object along a linear axis.

26. The method of claim 23 , wherein said interface apparatus is entirely on one side of a plane intersecting the pivot point such that the manipulatable object is on the other side of the plane from the interface apparatus.

27. The method of claim 23 , wherein said interface apparatus includes a closed loop spherical mechanism configured to provide the two rotary degrees of freedom to the manipulatable object about the remote pivot point.

28. The method of claim 23 , wherein a computer system coupled to the interface apparatus is configured to execute a medical simulation and display images associated with the medical simulation on a display.

29. A method as recited in claim 28 , wherein the medical simulation is a epidural anesthesia simulation, the manipulatable object including a needle having a syringe, and different physical property profiles are selected based on whether the needle is advancing or retracting in a simulated tissue of a simulated patient.

30. The method of claim 28 , wherein the determining the position of the manipulatable object includes determining whether the manipulatable object is positioned within a simulated tissue of a simulated patient.

31. The method of claim 30 , wherein the physical property profile is selected based on a trajectory of a simulated needle within the simulated tissue.

32. The method of claim 31 , wherein the selected physical property profile is operative to output forces simulating the simulated needle encountering a simulated bone.

33. The method of claim 23 , further comprising outputting forces from the actuator to compensate for a gravitational force resulting from a weight of at least one of the actuators such that the manipulatable object is configured to be manipulated substantially free from the gravitational force.

34. The method of claim 23 , further comprising transmitting the force from the actuator to the manipulatable object using a band drive mechanism including a capstan coupled to the actuator and a flat band configured to couple the to the spherical workspace.

35. An apparatus, comprising: a linkage including a plurality of members, the linkage configured to provide at least two rotary degrees of freedom about a pivot point spaced apart from said plurality of members, the pivot point located at an intersection of axes of rotation of at least two members from the plurality of members; a manipulandum coupled to at least one member from said plurality of members, said manipulandum being rotatable in said two revolute degrees of freedom about said pivot point; and a sensor configured to measure a rotation of the manipuladum and configured to provide at least one sensor signal associcated with a position of the manipulandum in the two revolute degrees of freedom.

36. The apparatus of claim 35 , wherein said plurality of members includes five members coupled in a closed loop such that each of said five members is pivotably coupled to two others members of said five members.

37. The apparatus of claim 35 , wherein said plurality of members are positioned only on one side of the pivot point, said plurality of members being provided within a hemisphere of a sphere defined such that said point is at a center of the sphere and the manipulandum is configured to be moved in a workspace that defines at least at portion of a surface of said sphere.

38. The apparatus of claim 35 , wherein at least a portion of said manipulandum extends through the pivot point.

39. The apparatus of claim 35 , wherein said manipulandum is independently translatable with respect to said linkage along a linear third axis in a third degree of freedom through the pivot point.

40. The apparatus of claim 35 , wherein said sensor is one from a plurality of sensors, each sensor from said plurality of sensors is coupled between two of said members of said linkage.

41. The apparatus of claim 35 , further comprising a plurality of actuators, each actuator from the plurality of said actuators is coupled between two members from the plurality of members of said linkage, each actuator from the plurality of said actuators configured to output a force.

42. The apparatus of claim 41 , further comprising a band drive mechanism coupled between one actuator from the plurality of said actuators and one member from the plurality of said members, said band drive mechanism configured to transmit the force to said manipulation and to transmit movement applied to said manipulandum to said sensors.

43. An apparatus, comprising: a plurality of members movable with respect to each other for providing at least one degree of freedon to a manipulandum; an actuator having a rotating shaft and configured to provide a force in one of the at leaset one degree of freedom of said manipulandum; a sensor configured to provide positions of said manipulandum in said at least one degree of freedon; and a band drive mechanism including a capstan and a flat band, said capstan being coupled to a first member from said plurality of members and to the rotating shaft of said actuator, said flat band being coupled to said capstan at a first end of said flat band and coupled to the first member at a second end of said flat band, said capstan being coupled to the first member by said flat band such that force is applied to the first member in the at least one degree of freedom when said rotating shaft of said actuator is rotated.